Abstract
Previous research on flood damage risk is updated using expected annual damage estimates from a recent U.S. Army Corps of Engineers (USACE) feasibility study in the Papillion Creek Watershed, Omaha, Nebraska. Across the 500-year floodplain study area encompassing all of the stream reaches in the Watershed, only 25% of 3,587 buildings were risk free. Commercial buildings represent 44% of inventory yet generate 92% of risk, which is double the previously estimated commercial risk based on simplistic modelling. Risk varies by building type, with office and recreation/entertainment buildings generating the highest amount (17% each) followed by industrial (12%), retail and warehouses (both at 11%), and apartments (6%). Mean annual risk values for buildings range from $160 (mobile homes) to $90,152 (recreation/entertainment). Only 11% of buildings in the study area were constructed over the 2005 to 2019 period (after the use of accurate floodplain maps and active floodplain planning), but they generate half of total flood risk. Omaha Area floodplain managers should focus more on commercial building flood risk to reduce the need for costly flood mitigation efforts funded by taxpayers. This research should be replicated elsewhere using either similar USACE feasibility study data, the National Structure Inventory dataset in conjunction with HAZUS-MH flood risk modelling, and/or private sector data from the First Street Foundation.
